When will autumn 2026 begin astronomically?

Approximately 18 days remain until the start of autumn in 2026.  

The autumnal equinox will occur on Wednesday, September 23, marking the end of summer and the beginning of a new season during which the weather will gradually improve, particularly with a decrease in temperatures and humidity levels.

Summer began astronomically on Sunday, June 21, ending with the start of autumn on September 23.

Autumn’s duration

Astronomical calculations for the seasons of 2026 reveal a difference in the duration of each season.

Spring began on Friday, March 20, and lasted 92 days and 17 hours, while summer began on Sunday, June 21st, and will last 93 days and 15 hours.

Autumn begins astronomically on Wednesday, September 23, and lasts for 89 days and 20 hours, while the winter season begins on Monday, December 21, and lasts for 88 days and 23 hours.

As autumn approaches, Egypt will gradually enters a transitional phase during which temperatures decrease.

However, this does not mean the sudden disappearance of summer weather, as some summer-like characteristics are expected to persist during the first half of September, particularly high temperatures and humidity levels.

Autumnal Equinox

The autumnal equinox occurs when the sun’s rays are almost perpendicular to the equator, resulting in approximately equal day and night lengths across most of the world.

Following the autumnal equinox, daylight hours gradually decrease while nighttime hours increase in the Northern Hemisphere, leading to a gradual change in weather patterns as autumn progresses.

Summer Solstice

The summer solstice occurred on Sunday, June 21, 2026, when the sun reached its northernmost point in the sky, coinciding with the Earth’s North Pole reaching its maximum tilt of approximately 23.5 degrees towards the sun.

This resulted in the longest day and shortest night of the year in the Northern Hemisphere.

The sun rose from its northernmost point in the northeast, and shadows cast at midday were the shortest of the year.

On the summer solstice, the sun appears to reach its highest and longest point in the sky as seen from the Northern Hemisphere, resulting in longer days than nights.

Daylight hours then gradually decrease as the autumnal equinox approaches.

Gradual Weather Change

With the arrival of autumn, a transitional phase begins.

Temperatures continue to decline gradually, while humidity levels decrease compared to the peak of summer, leading to increasingly mild weather as winter approaches.